Multi-Speed Torque Clutch in Power Tool Transmission

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Solution Overview

Problem

Existing power tools with torque clutches often have the torque clutch located at the input stage of the transmission, limiting flexibility in speed and torque adjustments, as they lack an improved multi-speed transmission configuration that allows for more versatile torque control at different stages.

Innovation Solution

A power tool design featuring a multi-speed transmission with a torque clutch positioned at a stage other than the input, utilizing a planetary gear system with movable ring gears and a clutch mechanism that adjusts torque output based on speed ratio settings, allowing for variable speed and torque configurations through a clutch assembly and speed selector mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the torque clutch is located at the input stage of the transmission, then the structure is simpler and more robust, but the flexibility in speed and torque adjustments is limited

Engineering Contradiction:
Improveflexibility in speed and torque adjustmentsVSAvoidtransmission system complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The transmission system is divided into multiple independent planetary stages (first stage, second stage, third stage), each with its own torque clutch (first torque clutch, second torque clutch). This segmentation allows each stage to be controlled independently, providing flexibility in speed and torque adjustments while maintaining a modular structure that doesn't excessively increase overall system complexity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements a dynamic transmission system where the torque clutches can be selectively engaged or disengaged based on operational requirements. The controller can dynamically switch between different clutch configurations to achieve various speed ratios and torque outputs, making the system adaptable to different working conditions rather than being fixed in a single configuration.

Inventive Principle:
Principle #15Dynamics

2Adaptability or versatility

If a multi-speed transmission with multiple planetary stages is used, then speed and torque control flexibility is improved, but the device complexity increases

Engineering Contradiction:
Improvespeed ratio settingsVSAvoidnumber of planetary stages
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The multi-speed transmission is segmented into three distinct planetary stages, each contributing to the overall speed reduction and torque multiplication. By dividing the transmission into separate stages rather than using a single complex stage, the system achieves multiple speed ratios while maintaining manageable complexity through modular design and independent control of each stage.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each planetary stage is designed to serve multiple functions: speed reduction, torque multiplication, and selective engagement through torque clutches. The first and second torque clutches can independently control their respective stages, allowing the system to achieve various operational modes (different speed ratios and torque outputs) using the same hardware configuration, thereby reducing the need for additional components.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Adaptability or versatility

If the torque clutch is positioned at a stage other than the input, then operational versatility is enhanced, but the manufacturing complexity increases

Engineering Contradiction:
Improvetorque control configurationsVSAvoidassembly complexity
Core Design Contradiction:
Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The transmission system is segmented into modular planetary stages with dedicated torque clutches at different positions (first torque clutch at input stage, second torque clutch at intermediate stage). This segmentation allows each module to be manufactured and tested independently before final assembly, reducing overall assembly complexity despite the enhanced torque control configurations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The torque clutches and planetary stages are pre-assembled as integrated modules before final system assembly. The first planetary stage with its torque clutch can be pre-configured, and the second planetary stage with its torque clutch can be pre-configured, allowing for quality control and testing at the module level before integration into the complete transmission system, thereby easing final assembly complexity.

Inventive Principle:
Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables more flexible and user-selectable torque and speed settings, enhancing the power tool's operational range and versatility by decoupling the torque clutch from the input stage, allowing for low, intermediate, and high-speed operations with controlled torque output.

Implementation Method 1

The multi-speed transmission includes a plurality of planetary stages with a first stage and a second stage that receives rotary power from the first stage. The first stage has a first internally toothed gear element and the second stage having a second internally toothed gear element.

Methodology Applied
Scientific EffectGear meshing: Gear

Implementation Method 2

The multi-speed transmission is configured to transmit rotary power between the motor and the output spindle and includes a plurality of planetary stages

Methodology Applied
Scientific EffectPlanetary gear mechanism: Epicyclic Gearing

Implementation Method 3

The torque clutch limits torque output from the multi-speed transmission to the output spindle. The torque clutch is configured to alternatively ground the second and third internally toothed gear elements to the housing through the torque clutch based on a speed ratio setting of the multi-speed transmission.

Methodology Applied
Scientific EffectFriction clutching: Friction

Data Source

PatentEP2614931B1Power tool with torque clutch
Publication Date: 2017.04.26 BLACK & DECKER CORP
  • EP2614931B1 patent drawingFigure 1
  • EP2614931B1 patent drawingFigure 2
  • EP2614931B1 patent drawingFigure 3

AI summary

A power tool that includes a housing, a motor, a trigger, a multi-speed transmission and a torque clutch. The housing define a handle. The motor is coupled to the housing. The trigger is coupled to the housing and configured to control operation of the motor. The multi-speed transmission is configured to transmit rotary power between the motor and the output spindle and includes a plurality of planetary stages with a first stage and a second stage that receives rotary power from the first stage. The first stage has a first internally toothed gear element and the second stage having a second internally toothed gear element. The torque clutch limits torque output from the multi-speed transmission to the output spindle. The torque clutch is configured to alternatively ground the second and third internally toothed gear elements to the housing based on a speed ratio setting of the multi-speed transmission.